Corwin, James V.
Ph.D. (Doctor of Philosophy)
Department of Psychology
Cerebrovascular disease--Treatment; Neglect (Neurology)--Treatment
In approximately 40% of all cases of right hemisphere stroke, patients experience a complex array of debilitating neurological deficits known as the neglect syndrome. This devastating and crippling condition is characterized by impairments in spatial and attentional processing, lack of affect, and unresponsiveness to the side of space opposite the brain lesion. Even following significant recovery, one of the major symptoms of neglect, extinction to bilateral simultaneous stimulation (extinction), often remains. Currently, there are no effective generalizable treatments of any kind for patients with neglect. A rat model of the neglect syndrome that demonstrates dramatic behavioral, anatomical, and pharmacological similarities to the human has been developed to investigate behavioral recovery of function from neglect. Studies utilizing the rodent model suggest that recovery from neglect may be due to plastic changes occurring in one area of the brain, the dorsal central striatum (DCS). Given the apparent role of the DCS in neglect and recovery from neglect, two important issues arise: is the DCS the site of drug action in studies that demonstrate acute behavioral recovery following systemic injection of the dopamine agonist apomorphine, and is the DCS involved in extinction, the most persistent symptom of neglect? Results from the current study demonstrate that direct infusion of apomorphine into the DCS, but not a more lateral striatal control area, was effective in producing acute behavioral recovery from neglect. This finding represents an important step in the development of dopamine agonist therapy in the treatment of humans with neglect. With regard to the second issue, prior to the current study, the importance of the DCS in extinction had not been investigated. Further, it was also unknown whether extinction was simply a less severe form of neglect or a unique behavioral phenomenon separate unto itself. Results from the current study demonstrate that DCS-lesioned animals, despite exhibiting neglect, do not exhibit extinction. This finding suggests that neglect and extinction are dissociable and do not share the same neural substrates. These findings are particularly important for the development of therapeutic interventions, suggesting that neural substrates other than those involved in neglect should be investigated.
Van Vleet, Thomas M., "Therapeutic effects of apomorphine on neglect following unilateral destruction of the medial agranular cortex" (2003). Graduate Research Theses & Dissertations. 6427.
vi, 124 pages
Northern Illinois University
Rights Statement 2